diff options
Diffstat (limited to 'configure.in')
| -rw-r--r-- | configure.in | 27 |
1 files changed, 17 insertions, 10 deletions
diff --git a/configure.in b/configure.in index 0109367..6a69413 100644 --- a/configure.in +++ b/configure.in @@ -867,19 +867,26 @@ AC_SUBST(UNIVERSAL_ARCH_FLAGS) # tweak BASECFLAGS based on compiler and platform case $GCC in yes) - # Python violates C99 rules, by casting between incompatible - # pointer types. GCC may generate bad code as a result of that, - # so use -fno-strict-aliasing if supported. - AC_MSG_CHECKING(whether $CC accepts -fno-strict-aliasing) + # Python doesn't violate C99 aliasing rules, but older versions of + # GCC produce warnings for legal Python code. Enable + # -fno-strict-aliasing on versions of GCC that support but produce + # warnings. See Issue3326 + AC_MSG_CHECKING(whether $CC accepts and needs -fno-strict-aliasing) ac_save_cc="$CC" CC="$CC -fno-strict-aliasing" - AC_CACHE_VAL(ac_cv_no_strict_aliasing_ok, - AC_TRY_COMPILE([],[int main() { return 0; }], - ac_cv_no_strict_aliasing_ok=yes, - ac_cv_no_strict_aliasing_ok=no)) + save_CFLAGS="$CFLAGS" + AC_CACHE_VAL(ac_cv_no_strict_aliasing, + AC_TRY_COMPILE([],[int main() { return 0; }], + CC="$ac_save_cc -fstrict-aliasing" + CFLAGS="$CFLAGS -Werror -Wstrict-aliasing" + AC_TRY_COMPILE([],[void f(int **x) {} int main() { double *x; f((int **) &x); return 0; }], + ac_cv_no_strict_aliasing=no, + ac_cv_no_strict_aliasing=yes), + ac_cv_no_strict_aliasing=no)) + CFLAGS="$save_CFLAGS" CC="$ac_save_cc" - AC_MSG_RESULT($ac_cv_no_strict_aliasing_ok) - if test $ac_cv_no_strict_aliasing_ok = yes + AC_MSG_RESULT($ac_cv_no_strict_aliasing) + if test $ac_cv_no_strict_aliasing = yes then BASECFLAGS="$BASECFLAGS -fno-strict-aliasing" fi |